1. Field of the Invention
The present invention relates to a linear actuator and more particularly to a linear actuator used for a generator, for example.
2. Description of the Related Art
A conventional linear actuator 80, as shown in FIG. 7, is disclosed in U.S. Pat. No. 4,349,757. A shaft 81 which is made of magnetic material is brought into reciprocation in a fixed stroke by a driving source (not shown). A plurality of permanent magnets 82 are located around the shaft 81 in the axial direction thereof. The polarities of the permanent magnets 82 are formed in the radial direction. A cylindrical stationary core 83 is located around the permanent magnets 82.
A plurality of sector configured members 84 which are made of magnetic material form the stationary core 83. The sector configured members 84 have slots 85. Each of the magnetic poles 86 which face the permanent magnets 82 is interposed between two adjacent slots 85. Coils 87 are wound around the magnetic poles 86.
In the above-mentioned linear actuator, it is very difficult to construct the device such that the cylindrical stationary core 83 is formed by an aggregate of the sector configured members 84 and the coils 87 are wound around the magnetic poles 86 which are located in the inner circumference portion of the cylindric stationary core 83.